lkml.org 
[lkml]   [2002]   [Sep]   [8]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
SubjectRe: LMbench2.0 results
From
Date
On Sun, 2002-09-08 at 00:44, Martin J. Bligh wrote:
> >> Perhaps testing with overcommit on would be useful.
> >
> > Well yes - the new overcommit code was a significant hit on the 16ways
> > was it not? You have some numbers on that?
>
> About 20% hit on system time for kernel compiles.

That suprises me a lot. On a 2 way and 4 way the 2.4 memory overcommit
check code didnt show up. That may be down to the 2 way being on a CPU
that has no measurable cost for locked operations and the 4 way being an
ancient ppro a friend has.

If it is the memory overcommit handling then there are plenty of ways to
deal with it efficiently in the non-preempt case at least. I had
wondered originally about booking chunks of pages off per CPU (take the
remaining overcommit divide by four and only when a CPU finds its
private block is empty take a lock and redistribute the remaining
allocation). Since boxes almost never get that close to overcommit
kicking in then it should mean we close to never touch a locked count.

-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/

\
 
 \ /
  Last update: 2005-03-22 13:28    [W:0.174 / U:7.544 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site